【作者】 武敏；

【导师】 严密；

【作者基本信息】 浙江大学 ， 材料科学与工程， 2011， 硕士

【摘要】 功能梯度材料是一种介于异质材料和复合材料之间的新型材料,可以满足在单一材料内部的不同部位实现不同功能的需要,具有广泛的应用前景。本论文基于组元磁导率差异,利用外磁场对磁性组元的磁驱动作用,设计、搭建了运动磁场驱动装置，分别采用垂直磁场驱动和平行磁场驱动两种方法制备了成分和性能连续变化的Ni/环氧树脂系功能梯度材料。通过金相显微镜、紫外可见分光光度计、高绝缘电阻测量仪和振动样品磁强计等手段,系统研究了Ni含量、磁场运动速度和磁场作用次数等因素对Ni/环氧树脂梯度材料成分分布、透光率、电阻率和归一化饱和磁化强度的影响。主要研究结果如下：采用垂直磁场驱动法制备的样品,Ni沿磁场运动方向梯度分布,透光率、电阻率和饱和磁化强度也沿该方向梯度变化。随着Ni含量由5wt.%增加至15wt.%,样品中Ni成分梯度逐渐增大,之后由于粒子间相互作用的迅速增大阻碍了粒子的迁移,Ni含量为20wt.%的样品成分梯度又降低。随着磁场运动速度由0.25 mm/s增加至3 mm/s,成分梯度逐渐减小。经磁场作用1次至5次,形成的成分梯度逐渐增大。磁场作用次数超过5次后,体系结构基本稳定。此外,Ni沿外磁场方向形成链状团簇,导致电阻率和归一化饱和磁化强度在与链状团簇垂直和平行的方向上产生各向异性。建立了磁性粒子在垂直驱动磁场中的物理模型,合理解释了实验结果。采用平行磁场驱动法制备的样品,Ni沿磁场方向呈梯度分布并形成链状团簇。随着Ni含量由5wt.%增加至20wt.%,样品中Ni成分梯度先增大后减小,Ni含量为15wt.%的样品成分梯度达到最大值。随着磁场运动速度由1 mm/s增加至20mm/s,样品成分梯度逐渐减小。经磁场作用2次至10次,形成的成分梯度逐渐增大。磁场作用次数超过10次后,体系结构基本稳定。更多还原

【Abstract】 Functionally graded materials (FGMs) are emerging as a new class of special materials between heterostructure materials and composite materials. They have been extensively used in many engineering fields with their continuous spatial distribution of components and resulted properties. Based on the distinct difference in magnetic susceptibility between components, two new magnetic-field-driving approaches were developed to prepare Ni/epoxy resin FGMs. Vertical and parallel magnetic-field-driving devices were designed and built to meet the need of experiments. The influences of Ni concentration, magnetic filed velocity and the action times on composition distribution, electrical resistivity, light transmittance and normallized saturation magnetization of Ni/epoxy resin FGMs were studied systematically by means of optical microscope, spectrophotometer, high resistance meter, vibrating sample magnetometer.The results are summarized as follows:The gradient of composition distribution, light transmittance, electrical resistivity and specific saturation magnetization were formed along the field moving direction in samlpes fabricated by vertical magnetic-field-driving method. With increasing Ni content from 5 to 20 wt.%, the composition gradient increased first and then decreased. As the magnetic field velocity increased from 0.25mm/s to 3mm/s, Ni gradient decreased. The composition gradient increased with adding the action times of magnetic field from 1 to 5. The system structure remained unchanged after 5 times of magnetic field action. In addition, the chain-like clusters of Ni were formed, which lead to the anisotropy of electrical resistivity and normalized saturation magnetization. A schematic model was proposed to explain the distribution of particles in gradient magnetic fields.Ni gradient and chain-like clusters were obtained along the field direction in samples prepared by parallel magntic-field-activated method. The composition gradient increased with the increase of Ni contents, and reached the maximum value at Ni= 15 wt.%. With increasing the velocity of magnetic field from 1 to 20mm/s, Ni gradient decreased. The composition gradient increased with adding the action times of magnetic field from 2 to 10. The system structure remained stable after 10 times of magnetic field action.更多还原